Field of the Invention
The present invention relates to a method for the manufacture of at least one three-dimensional flexible container, in particular for the cryogenic storage of biological substances.
Technological Background
Flexible pockets for the cryogenic storage of fragile biological substances such as blood are already known of from the prior art.
Some flexible plastic pockets have a particular three-dimensional geometry designed to limit the stress which can be applied at very low temperatures to the biological substances these pockets contain so as to minimize the loss of biological substances.
Thus already known from the prior art are flexible pockets designed for the cryopreservation of liquid biological samples, which pockets comprise two sheets of plastic material each having a three-dimensional geometry sealed on their periphery to define a storage space. These flexible pockets also comprise at least one port for accessing their storage space for the purpose of filling it with and/or emptying it of a liquid biological substance.
To manufacture these flexible pockets multiple different stages must be realized, including in particular the production of the sheets, the forming of each of these sheets independently one of the other so that they each have a particular geometry, the superimposing of the sheets thus formed and the joining by sealing of these with at least one connection element on their periphery.
However, it is noted that the manufacture of such a flexible pocket for cryogenic storage is not only time-consuming and expensive, it additionally exposes this pocket to a real risk of contamination of its internal surfaces delimiting the storage space.
By way of example, such contamination can occur during handling of the thus-formed sheets during the superimposition stage.
Obviously, if contamination of the internal space of the flexible pocket were to occur it could result in a contamination of the biological substance intended to be contained in the storage space of this pocket with germs which could be deadly for a patient undergoing treatment.
Such risk of contamination is also encountered in another method for the manufacture of a three-dimensional flexible pocket by means of thermoforming, in which an insert having a shape, a width and a thickness corresponding to the internal shape, width and thickness of the flexible pocket to be manufactured is placed between the two superimposed sheets.
No matter how much care is subsequently taken to sterilize thus-manufactured flexible pockets, naturally it cannot be fully guaranteed that all of the germs and/or particles have been eliminated.
The risk to the health of patients associated with the use of biological substances contaminated by infected pockets therefore renders these methods of manufacture unsuitable for medical applications.
Furthermore, these methods of flexible pocket manufacture by thermoforming do not permit easy and reliable production of complex storage structures comprising, for example, several storage chambers linked to one another by elements for fluid communication.
The reduced dimensions of each of these storage chambers compared with the dimensions of the mold presents significant problems when it comes to their individual forming and/or when it comes to reproducibility.
There is therefore an urgent need for a method for the manufacture of containers for medical applications permitting production of complex structures which have multiple storage chambers and/or elements for fluid communication, the shape of each individual element of these structures conforming to a predetermined and reproducible geometry.